update unittest for BpmHistogram
fix unittest for BpmRubato, as it now has a new output rubatoNumber
check for invalid negative magnitudeThreshold is obsolete, as SpectralPeaks can be used on db scale
update unittest for MonoMixer

AudioLoader will through exception on "empty.wav" complaining that it cannot read stream info, using "empty.ogg"
therefore. Fix md5 output left unconnected.
the same fix for unittest monomixer_streaming
the same fix for unittest for MonoLoader (empty.wav)
fix audiowriter unittest
use empty.aiff instead of empty.ogg
fix unittests for StereoDemuxer
noise_pink.wav was damaged, restore to correct version, fixes unittest for ReplayGain
fix unittest for BpmHistogramDescriptors, add empty.aiff to audio folder